Field of the Invention
The present invention relates to data storage devices with flash memory and flash memory control methods.
Description of the Related Art
Flash memory, a data storage medium, is common in today's data storage devices. A NAND flash is one common type of flash memory.
For example, flash memory is typically used in memory cards, USB flash devices, solid-state drives, and so on. In another application with multi-chip package technology, a NAND flash chip and a controller chip are combined in one package as an embedded multi-media card (e.g. eMMC).
The storage space of a flash memory generally provides a plurality of physical blocks, and each physical block includes a plurality of physical pages. To release storage space for reuse, an erase operation has to be performed on a block-by-block basis, to release space one block at a time. When updating data, the new data is written into a spare space rather than being overwritten onto old data, and the old data has to be invalidated. Thus, the storage space management of flash memory is more complex than other storage mediums. A controller design especially for flash memory is therefore called for.